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Tachometer Not Working, 3G Civic Si


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#1
ADDvanced

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The tach isn't working at all.  Where do I start?


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#2
CSPCRX

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Tells us about the car.  Stock? Any mods?  What motor?  Auto or manual?


Victor
86 B-Powered CRX SI (SMF Solo2, HPDE-4 NASA & TA-A Time Attack
07 Harley FXST Softail
12 Audi S4

#3
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86 Civic SI, 100% stock, no mods, rust free, owned by little old lady.

 

A couple years ago the tach would bounce around on the freeway and act crazy, but then it just.... stopped entirely.  Car still runs fine.   Not sure where to start.

 

You can see the car for a couple seconds in this video:


Edited by ADDvanced, 10 May 2021 - 08:22 PM.

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#4
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Signal comes from the distributor so I would check the plug at the distributor to ensure your getting a good connection.  


Victor
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07 Harley FXST Softail
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#5
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Ok, through random googling I found out this may be a sign of a failing ignitor module.   I pulled the distributor, and sho'nuff, the ignitor module is out of spec, continuity is not showing up at all between the A/B posts.   So.... off to find one fo those and see if it cures the problem.  It was behaving erratically, not just cutting in and out, but flopping all over the place when it was failing, so I'm guessing this one is donezo.

Second question:  My car is overheating.   I have drained the radiator and swapped out the temp sensor, but it still didn't help so I wired the sensor together so the radiator fan runs whenever the car is on.  It's still overheating.   

Could the radiator just be an old piece of shit/clogged?


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#6
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Sorry to hear it was more than just a connection but that makes sense.

 

cooling could be several things like water pump, thermostat or as you said the radiator.  Here is what I would do.

 

pull the cap and start the car cold.  Make sure radiator is full enough you can see the water from the cap opening.  Once it warms up you should see the water drop a little and start flowing.  Upper hose and lower hose should feel equally warm after this happens.  If the water doesn’t start to flow that may mean the thermostat is bad.  On those motors if your going that far, to replace the thermostat you might as well do the water pump for good measure.  
 

if you are seeing flow but seems sluggish could be an indication of a clogged radiator as well.

 

hope this helps


Victor
86 B-Powered CRX SI (SMF Solo2, HPDE-4 NASA & TA-A Time Attack
07 Harley FXST Softail
12 Audi S4

#7
letank

as for overheating.... check your radiator cap seal... my temperature gauge was acting up on slow down...  upper and lower radiator hoses had the right temperature differential, checked thermostat, fine...  so I Dc'ed the AC compressor so the AC fan would turn on as needed... one day, there was a small coolant puddle ... ah, ah, here was the culprit a failed 34 year old radiator cap...  a new radiator cap did the job, it has been fine since the last summer



#8
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Update!   Picked up a new ignitor since mine tested bad...  for a Prelude 2.0, found on Ebay for $17.   Good news is it works, car runs fine, so it's official, Prelude 2.0 ignitors are Civic Si/CRX si Ignitors, and WAY cheaper.

 

That said.... still no tach movement.   Dammit.  

 

What are the next steps?  Pull the cluster?   I don't know where I will find another one.


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#9
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Several clusters on eBay.  Sorry was hoping the issue was with the tach feed from the distributor.  I believe you can test to see if signal is coming from the distributor with a multimeter.  I would try that before buying a cluster.


Victor
86 B-Powered CRX SI (SMF Solo2, HPDE-4 NASA & TA-A Time Attack
07 Harley FXST Softail
12 Audi S4

#10
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Update:  Used a meter set to the HZ setting on the blue wire coming into the cluster, bigger connector, just right of center.   Was reading 50-60 hz and would go up/respond when I hit the throttle, so I would assume up to this point anyway, wiring is good.

Disassembled the cluster, see no visual signs of leaking caps/bad solder joints, so I guess I'm just lost.  Even traced teh traces with the meter and the signal is getting into the tach, it's just not doing anything.   

So I checked ebay, yeah, a few clusters, but some of them have WHITE graphics over a black background, but my OEM cluster has orange/amber graphics over a black background.  Other than that they look identical.   What's the difference between white and amber?


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#11
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Sorry I can’t help you with that.  Sounds like you at least isolated it.


Victor
86 B-Powered CRX SI (SMF Solo2, HPDE-4 NASA & TA-A Time Attack
07 Harley FXST Softail
12 Audi S4

#12
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God dammit.  New cluster came in.  STILL no tach.

 

So I've replaced the ignitor, it seems like the lead on the harness is providing a signal... wtfffff


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#13
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That sucks!  Something has to have changed, so you had a tach then it stopped.  I would check resistance from the cluster connector to the connector at the distributor.  Just to rule out a short that’s reducing signal strength.


Victor
86 B-Powered CRX SI (SMF Solo2, HPDE-4 NASA & TA-A Time Attack
07 Harley FXST Softail
12 Audi S4

#14
greasemonkeyreborne 5x1g's

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that igniter crosses over several cars. i bought a couple a few years back from a dealers nos stock for the 80’s teg

i have no experience w ur situation. but have been having lightbulb and headlights go out on my 87 crxsi. wiggling connectors actually fixes it. so pull ur ecu connectors. wipe w alcohol. run them in and about 5 times and see if that does anything

please keep us posted. after 35 years, we’re getting weird stuff happening. these cars aren’t rocket science. someone will figure it out. please keep us posted

oh, i did have a fuse box terminal widen out where it intermittently shut off the radio. had to bend it back tighter and reinsert fuse.

point. check connectors
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#15
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I've wiggled the instrument harness, and all the harness under the hood, 100% dead, either cluster.   Driving me insane.  


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